A Structural Equation Modeling Approach to Fatigue-related Risk Factors for Occupational Injury

Abstract

Occupational injury is associated with numerous individual and work-related risk factors, including long working hours and short sleep duration; however, the complex mechanisms causing such injuries are not yet fully understood. The authors used structural equation modeling (SEM) as a novel approach to examine fatigue-related direct and indirect potential risk factors for occupational injury. The study sample contained 89,366 employed workers from the National Health Interview Survey (pooled across 6 years, 2004-2009), an annual survey of a representative cross-sectional sample of the US population. Direct and indirect effects of weekly hours worked and usual sleep duration on occupational injuries were modeled using SEM procedures for dichotomous outcomes and a complex sampling design. Confounding and mediating effects of gender, age, race/ethnicity, occupation, industry, type of pay, body mass index (BMI), and psychological distress were simultaneously examined. Long working hours and short sleep duration independently increased the risk of injury. Additional direct risk factors were gender, occupation, type of pay, and BMI. At the same time, sleep duration mediated the adverse relations of long working hours, high psychological distress, and high BMI with injury. These findings indicate that SEM is a useful approach with which to examine dichotomous outcomes and indirect effects in complex samples, and it offers a comprehensive new model of injury prediction.

For better or worse? Changing shift schedules and the risk of work injury among men and women

“…Occupational characteristics (ie, job permanency, usual weekly hours worked, physical demands, and number of employees in the organization) provided information about working conditions that may be associated with the risk for a work injury. Those new to a work situation, such as those starting a job, who work a greater number of hours, or who work in large organizations have been found in previous research to have increased risks of work injury (29)(30)(31)(32)(33).…”

Long Working Hours and Shift Work as Risk Factors for Occupational Injury

“…Based on the National Health Interview Survey in 2004-2009 (n=89,366), 10-hour increase in weekly working hours increased the injury risk by 14% (OR = 1.14, 95% CI 1.06-1.22) and 1-hour decrease in sleep increased the injury risk by 10% (OR = 1.10, 95% CI 1.02-1.19, p<0.01). In addition, long working hours increased the risk of short sleep duration (p<0.05), which in turn increased occupational injury risk [82] In the Thai Cohort Study in 2009 (n=51,751), women working over 49 hours per week had 1.4 times (OR = 1.4, 95% CI 1.1-1.9) more occupational injuries and men working as much as women had 1.3 times (OR = 1.3, 95% CI 1.0-1.6) more injuries than those working 40 hours per week [83]. These studies show that the risk of occupational injury is almost double when working hours exceed 60 per week compared to 40 hours per week.…”

Mediating pathways and gender differences between shift work and subjective cognitive function

“…Path modelling was used to gain a better understanding of the complex direct and indirect relationships between shift work, stress, sleep and subjective cognitive function 45. The benefit of path modelling over traditional regression methods is that it can examine direct and indirect pathways between distal (eg, shift work) and proximal predictors (eg, sleep, age, health, stress) with the outcome measure (cognitive function) 46.…”